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Propionic acid

Propanoic acid
Simplified skeletal formula
Full structural formula
Ball-and-stick model
Space-filling model
Names
Preferred IUPAC name
Propanoic acid
Other names
Propionic acid
Ethanecarboxylic acid
Identifiers
79-09-4 YesY
3D model (Jmol) Interactive image
Interactive image
ChEBI CHEBI:30768 YesY
ChEMBL ChEMBL14021 YesY
ChemSpider 1005 YesY
DrugBank DB03766 YesY
ECHA InfoCard 100.001.070
EC Number 201-176-3
E number E280 (preservatives)
1062
PubChem 1032
RTECS number UE5950000
Properties
C3H6O2
Molar mass 74.08 g·mol−1
Appearance Colorless, oily liquid
Odor Pungent, rancid, unpleasant
Density 0.98797 g/cm3
Melting point −20.5 °C (−4.9 °F; 252.7 K)
Boiling point 141.15 °C (286.07 °F; 414.30 K)
Sublimes at −48 °C
ΔsublHo = 74 kJ/mol
8.19 g/g (−28.3 °C)
34.97 g/g (−23.9 °C)
Miscible (≥ −19.3 °C)
Solubility Miscible in EtOH, ether, CHCl3
log P 0.33
Vapor pressure 0.32 kPa (20 °C)
0.47 kPa (25 °C)
9.62 kPa (100 °C)
4.45·10−4 L·atm/mol
Acidity (pKa) 4.88
-43.50·10−6 cm3/mol
Thermal conductivity 1.44·105 W/m·K
1.3843
Viscosity 1.175 cP (15 °C)
1.02 cP (25 °C)
0.668 cP (60 °C)
0.495 cP (90 °C)
Structure
Monoclinic (−95 °C)
P21/c
a = 4.04 Å, b = 9.06 Å, c = 11 Å
α = 90°, β = 91.25°, γ = 90°
0.63 D (22 °C)
Thermochemistry
152.8 J/mol·K
191 J/mol·K
−510.8 kJ/mol
1527.3 kJ/mol
Hazards
Main hazards Corrosive
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Danger
H314
P280, P305+351+338, P310
Corrosive C
R-phrases R10, R34
S-phrases (S1/2), S23, S36, S45
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 54 °C (129 °F; 327 K)
512 °C (954 °F; 785 K)
Lethal dose or concentration (LD, LC):
LD50 (median dose)
1370 mg/kg (mouse, oral)
US health exposure limits (NIOSH):
PEL (Permissible)
none
REL (Recommended)
TWA 10 ppm (30 mg/m3) ST 15 ppm (45 mg/m3)
IDLH (Immediate danger)
N.D.
Related compounds
Other anions
Propanoate
Acetic acid
Lactic acid
3-hydroxypropionic acid
Tartronic acid
Acrylic acid
Butyric acid
Related compounds
1-Propanol
Propionaldehyde
Sodium propionate
Propionic anhydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Propionic acid (from the Greek words protos, meaning "first", and pion, meaning "fat"; also known as propanoic acid) is a naturally occurring carboxylic acid with chemical formula CH3CH2COOH. It is a clear liquid with a pungent and unpleasant smell somewhat resembling body odor. The anion CH3CH2COO as well as the salts and esters of propionic acid are known as propionates (or propanoates).

Propionic acid was first described in 1844 by Johann Gottlieb, who found it among the degradation products of sugar. Over the next few years, other chemists produced propionic acid in various other ways, none of them realizing they were producing the same substance. In 1847, the French chemist Jean-Baptiste Dumas established all the acids to be the same compound, which he called propionic acid, from the Greek words πρῶτος (prōtos), meaning first, and πίων (piōn), meaning fat, because it is the smallest H(CH2)nCOOH acid that exhibits the properties of the other fatty acids, such as producing an oily layer when salted out of water and having a soapy potassium salt.

Propionic acid has physical properties intermediate between those of the smaller carboxylic acids, formic and acetic acids, and the larger fatty acids. It is miscible with water, but can be removed from water by adding salt. As with acetic and formic acids, it consists of hydrogen bonded pairs of molecules as both the liquid and the vapor.


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